The present application relates to coolable airfoils of the type used in high temperature rotary machines such as gas turbine engines.
Efficiency is a primary concern in the design of any gas turbine engine. One principle technique to increase engine efficiency is elevation of core gas path temperatures. Internally cooled components manufactured from high temperature capacity alloys accommodate these elevated temperatures. Turbine stator vanes and blades, for example, are typically cooled using compressor air worked to a higher pressure, but still at a lower temperature than that of the engine core gas path.
Airfoil cooling may be accomplished by external film cooling, internal air impingement and forced convection either separately or in combination. In the attachment section of an airfoil, space between the faces of fir-tree lobes in the rotor blade attachment provides for passage of cooling air. The space, however, may be too small for effective cooling flow at the elevated core gas path temperatures of high efficiency gas turbine engines.